264 THE PRESENT EVOLUTION OF MAN 



caused by the direct action of the environment) is based in part, 

 apparently, on a tradition ultimately derived from popular notions 

 and first acquired by us all in the nursery, and in part on experi- 

 ments and statistics which as a rule have no bearing on the point 

 at issue. The problem, as we have already noted, is not whether 

 it is possible to devise conditions in which the germ-plasm is 

 injured beyond recovery, but not destroyed, but whether under 

 conditions more or less normal to the race variations are commonly 

 caused by the direct influence of the environment. 1 Disease, 

 which at one time or another affects practically every individual 

 in England and Africa, has for thousands of years been almost 

 as normal an occurrence as birth itself. 



438. The experiments on which medical men rely are such as 

 are afforded by Clayton's beans, 2 transplanted Alpine plants, 

 Fere's alcoholized eggs, 3 and the like. The experiments they 

 ignore are those of nature which every day's professional work 

 brings under their notice, but over which hangs the veil of famili- 

 arity. The statistics they rely on are such as alienists collect. 4 



1 See 1 60. 2 See 134, 156. 



3 I think it would puzzle anyone who tries to think clearly to explain how 

 Fere's perpetually quoted experiments bear on the problem of the causation of 

 variations. Fere exposed eggs to the vapour of alcohol and got some remarkably 

 miserable chickens. This indicates that alcohol is bad for developing chickens. 

 It does not indicate that the ill-effects are germinal and therefore ' innate ' and 

 ' transmissible ' to descendants any more than a plucked chicken indicates that 

 the effects of plucking are ' inheritable.' Fere should have bred from his de- 

 debauched chickens. The attitude of some medical men, who are interested in 

 philanthropy, especially temperance reform, and who have been accustomed to 

 insist on the ' degeneracy ' which results from insanitation and drink, is instructive 

 from the point of view of scientific education (see 1 16, footnote). The statement 

 that ill-conditions cause protective evolution, not racial deterioration, is often 

 declared by them to be too ' philosophical ' or ' academic ' or ' logical.' ' Honest 

 facts ' are demanded. It is hard to say what is meant exactly possibly nothing 

 more than that the masses of fact on which the statement is founded are large 

 and complex, and the thinking necessary before the relations can be ascertained 

 somewhat difficult. The fact that diseases cause evolution, not deterioration, if 

 not honest, is at least indisputable. I imagine by honest is meant experimental. 

 The statement that " we know very little about heredity " has no doubt very 

 often an element of truth ; but the version that " very little is known about 

 heredity " is distinctly inaccurate. Sometimes it is said that " the proposition 

 that germ-cells are inviolable is sheer nonsense. They are just as liable to injury 

 as other cells, and we have daily experience that somatic cells may be injured." 

 But no one has maintained that germ-cells are inviolable. It has only been 

 maintained that all kinds of cells, including the germ-cells of all species, have 

 been so dealt with by Natural Selection that they hold to their hereditary 

 tendencies almost as firmly as they hold to life. 



*See 131, 135. 



